1. Field of the Invention.
The present invention relates to methods for waterproofing concrete and concrete-like structures and, more particularly, to an injection packer and apparatus for waterproofing concrete and concrete-like structures.
2. Description of the Related Art.
Concrete and other similar substances have been known and used for many years. However, no matter how much care is taken in the preparation or placement of concrete and concrete-like structures cracks, voids, and fissures can develop causing various problems. The problem of cracking or of defective joints in concrete structures is a source of concern. One type of problem associated with cracks, voids, fissures, and/or defective joints is water leakage. Water leakage into basements, tunnels, pits, and other concrete structures as a result of cracks and/or other defects in the concrete is of great concern and as old a problem as concrete itself. Cracks can be categorized into 1) intermittent leaking; and 2) constant or continuous leaking. Intermediate or "non-active" leaking includes leaking only when the water table reaches a particular level, such as will occur immediately after a rain. Constant leaking or "active leaking" as it is known in the industry, is water that is constantly running through the concrete structure via a crack, defect, or the like.
Various remedies have been devised in an attempt to remedy or stop intermittent leaking including the use of mortars and epoxies as sealing and/or patching agents since such materials may be used during the dry spells. Both mortars and epoxies are relatively effective when leaking is not present in that they bond quickly and provide a rigid repair. However, over time such repairs can also crack.
Active leaks are much more difficult to contain. Mortars, epoxies and similar materials are not practical in active leak repair since they cannot "set up" or cure to hardness in the presence of running water. Therefore, such methods as gutters, trenches, and other water diversion methods are used to alleviate active leaking. In contrast, a non-diversion method for stopping water that enjoyed success upon introduction was the use of polyurethane resins. When polyurethane resins are injected under pressure into the concrete, the polyurethane resins expand upon contact with the moisture. Polyurethanes can be divided into two major categories characterized by their reaction to water, hydrophobic and hydrophilic. Hydrophobic polyurethanes use water as a reacting agent only, thus absorbing very little water. The cured material is relatively free of water making it very resistant to post-cured shrinkage. Hydrophilic polyurethanes can incorporate large quantities of water thereby creating shrinkage within the cured material as the incorporated water evaporates. Hydrophobic polyurethanes are generally more versatile and are suited for concrete crack injection. Since the introduction of polyurethanes, various polyurethane formulations have been devised.
Polyurethane formulations are today injected directly into the water flow where they react with the water. The reaction causes the polyurethane formulation to expand into a strong, sticky foam to obstruct continued flow. Reaction times vary with respect to the particular polyurethane formulation used. Use of an accelerator added to the polyurethane can speed up reaction or gel time depending on the rate of water flow. If the water is flowing quickly, a rapid "gel" accelerator is added to the polyurethane resin formulation. This causes the polyurethane resin formulation to react before the resin is flushed from the crack. If the water flow is low, a small amount or accelerant may be used, if any at all. Of course, the less accelerant used the slower the reaction or cure time of the resin. Another consideration is that less accelerant allows a greater amount of resin to be injected into the crack and time to work with it as well.
Once the resin is introduced into the water stream, it must have time to react before it is flushed from the void by the moving water. One technique that allows the polyurethane to gel, is to drill injection holes diagonally to intersect the structural crack or void some distance from the structure surface. Generally, a 5/8" bore size is used for the hole. Smaller drill bits for smaller bore sizes may be too fragile to drill the deep holes usually required.
In utilizing the boring technique, the porting connection at the hole presents a challenging problem. The porting connection must be made against a flowing stream of water (active flow) without leaking. Further, the porting connection must withstand resin injection pressures of over 3,000 psi (pounds per square inch). Devices for the porting connection are referred to as "packers."
There are in general two types of packers: 1)expanding, and 2) non-expanding. The non-expanding are tapered plugs with a hole through their length, and a grease, or other type of fluid coupler, fixed at the external (fat) end of the plug. The non-expanding plugs are driven into the holes until they are stuck fast. The resin connection is made at the external fitting. The non-expanding plug types work fairly well in smaller holes, but are seldom used in 5/8" diameter holes where the pressure against them is greater due to the larger diameter of the hole.
There are two types of expanding packers. One type is similar to the non-expanding plug described above, except that the tapered plug is threaded externally and screwed into a plastic sleeve that is forcibly expanded as the plug advances within it. The sleeve expands until it and the plug are bound within the hole. The resin is then injected through the zerk type grease fitting thereon. A problem with both types of plugs described above is that such plugs are tapered, and as a result, the expansive force is focused on a relatively narrow ring. This allows less surface contact to provide the friction to resist the fluid pressure.
The second type of expandable plug is the most widely used. It consists of a metal tube with an exterior straight thread running its entire length and an interior pipe thread at one end. The interior thread accepts a zerk type grease fitting or the like for the resin hose connection. The exterior thread supports two nuts and their washers, one at each extremity of a rubber tube segment. As the nut at the front of the packer is rotated, the nut advances on the stem to compress the rubber tube segment disposed between the two washers, thereby expanding the rubber segment and binding the packer against the wall of the hole. The resin is then injected through the zerk type fitting.
However, such packers as described above present several problems. First, such packers are costly. Second, such packers are extremely difficult to remove from the injection hole. The projecting segment of such packers may be broken off, leaving a portion of the packer within the hole. However, leaving a portion of the packer within the hole creates a problem if the hole is to be patched. Removal of the packer may require chipping, prying, and sometimes drilling. In some applications, metal packers having ferrous components must be completely removed in order to prevent corrosion within the wall. Expansive forces exerted by corrosion may cause the concrete to spall or leach objectionable stains.
Full extraction of metal packers is extremely difficult. Initially, the stem or nut must be rotated counter-clockwise to relax the rubber segment. If the stem rotates, the nut and its washer may become disengaged and left within the hole where they are then almost impossible to extract. If the forward nut is loosened and the rubber segment is relaxed, the stem can be gripped and pulled from the hole. If the polyurethane material has even partially set or cured, removal becomes even more difficult. A vise grip type tool is usually used in such attempts as the device has no feature which lends itself to gripping for removal.
Also, holes drilled at an angle into concrete are sometimes oversize and eccentric for a depth of approximately an inch as the drill bit defines its drilling direction. This especially holds true when dealing with poor concrete. In such cases, the hole or bore diameter only becomes true and consistent after the drill bit becomes more confined within its own bore. When a hole is oversize and eccentric at the beginning, expanding rubber packers are difficult to set because they are too short to reach the concentric diameter of the bore needed to grasp the rubber hose segment. If the rubber hose segment of the packer is not grasped by the hole by contact with the walls of the hole, the entire packer assembly will spin as the nut thereof beneath the zerk is rotated. This difficulty is usually overcome by removing the packer and advancing one of the nuts to compress, and thereby expand, the rubber hose segment sufficiently to gain friction against the walls of the hole when the packer is re-inserted.
Worn bits can also be a source of eccentric and undersized holes. When holes are undersized as a result of worn bits, it is difficult to insert expanding rubber type packers. Such packers cannot be driven into the hole without danger of damaging the zerk fitting.
Yet another problem with such packers is that, due to the above problems, they seldom withstand the injection pressures sought by most contractors.
What is thus needed in the industry is a cost effective packer.
What is further needed in the industry is a packer that can be easily and fully removed.
What is still further needed in the industry is a packer that can withstand injection pressures of 4,000 psi in a 5/8" diameter hole, yet offer easy and full removal.
What is still further needed in the industry is a packer that can place its expansive, or compressible, sealing component beyond the proximate, and usually eccentric, hole segment.
What is yet further needed in the industry is a packer that can be easily inserted into a slightly undersized hole without damage to the packer.